A combine harvester has a cleaning system for separating harvested seeds from by-products that are harvested along with said seeds.
Combine harvesters are widely used in the harvesting of various types of grain, corn and other crops of which the seed is harvested. Typically, a combine harvester cuts the plants that contain the seeds to be harvested from the field. The harvested crop is threshed inside the combine harvester, in which process the seeds are separated from the other parts of the plants. The stalks of the harvested plants are removed from the combine harvester and a mixture of harvested seeds and by-products remains in the combine harvester.
The mixture of harvested seeds and by-products is transported to a cleaning system, in which the threshed seeds are separated from the by-products. The cleaning system generally comprises one or more sieves, which perform a reciprocating movement during use. The sieved seeds are then collected and transported to the grain tank of the combine harvester, which is generally emptied periodically.
Relevant examples of cleaning systems are described in U.S. Patent Application Publication Nos. 2016/0029562 and 2015/0296712, each of which is incorporated by reference herein in its entirety for all purposes. The location of a cleaning system in a combine is shown in U.S. Patent Application Publication No. 2015/0296712.
The sieve or sieves of the cleaning system are generally arranged at an angle relative to the horizontal, with the front end of the sieve lower than the rear end of the sieve. It is known to arrange the sieve on rocker (i.e., shaker) arms and to drive the sieve in a reciprocation motion via an eccentric device in combination with a pitman arm. The eccentric device may comprise a crank or an eccentric disc that is driven by an input drive.
The reciprocating movement of the sieve causes the seeds and by-products to be thrown upwards and backwards by the sieve. More particularly, the reciprocation sieve movement comprises a throw stroke and a return stroke. During the throw stroke, the sieve throws the harvested seeds and by-products upward from the sieve. During the return stroke, the sieve moves back from the end position of the throw stroke to the beginning position of the throw stroke. The harvested seeds and by-products are airborne during most of the return stroke of the sieve. A fan blows the airborne lighter weight by-products towards the rear of the combine. The harvested seeds and remaining by-products fall back onto sieve during the last part of the decelerating portion of the return stroke.
The reciprocating sieve movement has several movement parameters, including stroke length and throwing angle. The sieve stroke length is the distance between the foremost position and the hindmost position of the sieve during the sieve movement. The sieve throwing angle is the angle at which the grain is thrown up from the sieve during the reciprocating movement of the sieve.
To adjust the throwing angle of a sieve in a typical combine, it is often necessary to remove the entire rocker arm and then reposition that rocker arm to a different angle. It would be desirable to provide a simple way to adjust the throwing angle of a sieve without either removing or completely removing the rocker arm.